A man has been arrested in Bristol after a Labour MP and a campaigner were subjected to a torrent of violent abuse on Twitter.

The 32-year-old man was held following allegations made by Labour MP Stella Creasy and campaigner Caroline Criado-Perez, who received a barrage of threatening messages from internet trolls on the micro-blogging site.

The suspect will be questioned at a local police station on suspicion of committing an offence under the Protection from Harassment Act.

The suspect is the third person arrested over the aggressive stream of messages, which included threats of rape.

The arrest came as Scotland Yard's e-crime unit examined allegations of abuse made by eight people on the site.

The episode has prompted calls for Twitter to beef up its security procedures.

More than 120,000 people have signed a petition urging Twitter to implement tighter processes to protect its users.

The site has moved to clarify its rules on abusive behaviour and drafted in extra staff to handle attacks by trolls.

Ms Criado Perez, who successfully fought for a woman's face to appear on £10 banknotes, spoke out after she was targeted online last month.

Walthamstow MP Ms Creasy drew a similar tirade of sexually aggressive messages after she offered her support of the campaigner.

A number of female journalists later came forward to report a series of rape and bomb threats.

They were allegedly sent to Guardian columnist Hadley Freeman, Independent writer Grace Dent and Europe editor of Time magazine Catherine Mayer. Similar messages were also sent to Sara Lang, a social media manager at US campaign group AARP.

Twitter has said it plans to make reporting abuse easier by bringing a "report abuse" function already available on the iPhone app version of the micro-blogging site to other phones and platforms.